1. M. Adorni, F. Arcelli, D. Ardagna, L. Baresi, C. Batini, C. Cappiello, M. Comerio, M. Comuzzi, F. De Paoli, C. Francalanci, S.Grega, P. Losi, A.Maurino, S. Modafferi, B. Pernici, C. Raibulet, F. Tisato The MAIS approach to web service design Porto 13 June 2005 Andrea Maurino Università di Milano Bicocca maurino@disco.unimib.it

2. The MAIS approach to web service design 2Outline  The MAIS Project  The MAIS Methodological Framework General view  Service Specification and Compatibility Analysis  Broker-Provider Negotiation and Dynamic Evaluation of Management Costs  Process Partitioning  Optimal Service Selection and Quality Renegotiation  Implementation Guidelines for a QoS-Oriented Reflective Architecture  Conclusions and future work

3. The MAIS approach to web service design 3 The MAIS Project  Multichannel adaptive IS  Italian Research Project (2002-2005)  Partners: 6 universities Politecnico di Milano (coordinator) University Milano Bicocca University of Roma La Sapeinza University of Roma Tre University of Lecce – ISUFI University of Brescia 2 research centers CEFRIEL IFAC-CNR 2 companies ST Microelectronics Engineering

4. The MAIS approach to web service design 4 The MAIS Project  Develop methods, models, and architectures for multichannel adaptive information systems  Multichannel Service provisioning: web, e-mail, sms, client-server Mobile information systems  Heterogeneity, dynamic evolution of channels Device characteristics Network connections  Adaptation to context User model Service provisioning Channel of invocation, QoS

5. The MAIS approach to web service design 5 Research focus  Adaptive orchestration of e-services  Reflexive architecture for context-aware services  Design of web Services with QoS  Adaptive networks  Low power consumption processors  Methods and tools for multichannel interface design and integration  Application areas: e-learning, tourism, emergency teams

6. The MAIS approach to web service design 6 The MAIS Project S1.op1 S1.op2 S1.op3 S2.op1 S2.op2 S2.op3 - access to e-services - cooperative processes - Tourism - E-learning - Risk management

7. The MAIS approach to web service design 7 The MAIS methodological framework  4 Methodological steps  Requirements Analysis elicit, validate and negotiate web service requirements Multichannel, QoS  Design model services with MAIS-UML  Deploy Network infrastructure  Run time adaptive and context-aware use of web services

8. The MAIS approach to web service design 8Framework

9. 9 Service Specification and compatibility analysis  Analysis, (re)-design of web service Use of MAIS QoS, Services and Channel Ontology  3 sub-phases:  functional service modelling, Model requirements thanks UML Logical and operational structure of Web Services  high-level redesign Augment existing schema with QoS dimension (from the MAIS QoS ontology) Modelled with MAIS-UML profile Metrics QoS dimensions have a ( B k) ) quality level

10. The MAIS approach to web service design 10 Service Specification and compatibility analysis  Context adaptation Verification of quality values of QoS requirements and Quality thresholds  Comparison between B k of each QoS and ideal level request by user  QoS tree  Simple Additive Weighting technique Weights and composition rules to each node

11. The MAIS approach to web service design 11 Process Partitioning  New deployment strategies for MobIS  Goals: improve the independency among actors Reduce interaction and knowledge sharing  Solution: decompose a unique process into a set of sub process Automatic partitioning rules Based on graph transformation systems  Input: MAIS-UML (translated into MAIS-BPEL), network topology  Output: set of MAIS-BPEL  Some formal and empirical result on the correct behaviour of sub process

12. The MAIS approach to web service design 12 Optimal Service Selection and Quality Renegotiation  Goal: select from registry a set of services functional equivalent service  Optimization problem with two difference approach  Select at run time the best candidate service which supports the execution of a running high level activity. (local level) Service can be selected if its price is lower than a given threshold  Identiy the set of candidate services which satisfy end-user preferences for an entire application (global level) the total price has to be less than 2$.  Service composition with QoS modelled as a mixed integer linear programming problem NP-hard !!! Multiple Choice Multiple Dimension Knapsack problem We use CPLEX, a state of the art commercial solver, which implements a branch and cut technique

13. The MAIS approach to web service design 13 Broker-Provider Negotiation and Dynamic Evaluation of Management Costs  Broker between provider and users  Conflicting Goals Maximize the satisfaction of user requirements Achieve maximum possible returns from its brokering role  Broker is paid each time a service is supplied by user  Broker can increase the QoS offered by provider  Preliminary phase set the value of a triple p ij :price paid by the user for the service, perc ij :is the percentage on the price due by the service provider to the broker (0 and 1) q ij is the aggregate value of QoS offered to user (0 ≤ q i j ≤ 1).

14. The MAIS approach to web service design 14 Broker-Provider Negotiation and Dynamic Evaluation of Management Costs  Negotiation processes is realized by means of Negotiation Protocol: bilateral bargaining protocol; Negotiation Objectives: typical multiattribute problem: negotiation of a triple of attributes Decision Model: trade-off based strategy  Utility function V evaluate how much an offer is worth to a participant  Increase QoS level  an extra cost c * (q ij ), provide the service to the customer at a higher price p * (q ij )  Modify selection of web services in case of cooperative process  Even in the design phase

15. The MAIS approach to web service design 15 Implementation Guidelines for a QoS-Oriented Reflective Architecture  Architectural reflection introduces a reflective layer applications can observe and control at execution time non- functional features of the system components, supporting adaptability.  A reflective layer is causally connected to the physical layer.  Components and QoS cannot be defied in absolute way domain-dependent QoS like “low”, “medium”, “high”  Definition of QoS extension pattern

16. The MAIS approach to web service design 16 Implementation Guidelines for a QoS-Oriented Reflective Architecture  R_Object expose measurable QoS values Controlled/observed Model high-level/domain-dependent abstraction  R_aggregate casually connected to QoSStrategy to set of QoS  QoSStrategy How QoS is obtained/mapped

17. The MAIS approach to web service design 17Conclusion  Propose of a methodological framework From Analysis to run time execution Fusion of several contributions  Future works  Evolution of each component according to the specific research problem  Extension of our proposal to include MAIS results for the front-end Integration Validation